1. Field of the Invention
The present invention relates to an array substrate, method of disconnection inspecting a gate lead wire and a source lead wire in the array substrate, a method of inspecting the array substrate, and a liquid crystal display device.
2. Description of the Background Art
In process of manufacturing a liquid crystal display panel, an inspection of disconnection in an array substrate in which a circuit for display is formed on glass, a defect of a pixel, or the like is performed. Concretely, by writing charges in pixels constructing a display region and reading the charges, an inspection for disconnection in a gate signal line and a source signal line in a semiconductor switching element, a defect of a pixel, and a failure of a semiconductor switching element is performed.
The inspection is generally sequentially performed by bringing probes into contact with inspection terminals provided for gate signal lines and source signal lines in a lump, supplying an inspection signal to the gate signal lines and the source signal lines, and causing semiconductor switching elements formed at intersecting points to operate.
As inspection terminals, generally, terminals (mounting terminals) for mounting a semiconductor chip and an FPC in a later process are used or inspection terminals are separately provided near mounting terminals. By providing inspection terminals in such a part, disconnection in wires (lead wires) from the inspection terminals to the display region can be also detected.
In the above-described array substrate inspecting method, in the case of performing probing on mounting terminals, a probe unit corresponding to the mounting terminal has to be fabricated. As the resolution of display panels is becoming higher and the density of semiconductor chips is becoming higher, there is the tendency that the number of probes constructing a probe unit increases, and the probe interval becomes narrower, and it is becoming difficult to fabricate the probe unit.
On the other hand, methods of performing an inspection for disconnection in gate signal lines and source signal lines of semiconductor switching elements provided in a display region of a display panel, a defect of a pixel, or the like by turn on or off of pixels of the display panel are also known. As one of the inspection methods, there is a known method of performing an inspection on a plurality of gate signal lines and a plurality of source signal lines in a lump by bringing probes into contact with inspection terminals and controlling supply of inspection signals to the plurality of gate signal lines and the plurality of source signal lines by a plurality of semiconductor switching elements for inspection connected to the signal lines in a lump.
In such a lump inspection method, different from an inspection method of probing each of the plurality of gate signal lines and the plurality of source signal lines, an inspection device is not influenced by the resolution of a display panel and design (for example, the number of bumps) of a semiconductor chip, so that the general and inexpensive inspection can be realized.
In the inspection method, conventionally, a lighting inspection circuit including the plurality of semiconductor switching elements for inspection and the like is provided in a semiconductor chip mounting region in which a semiconductor chip is to be mounted. However, as the size of semiconductor chips is becoming smaller and the frame of the display panels is becoming narrower, the size of the semiconductor chip mounting region has to be decreased. Consequently, it is considered to divide the lighting inspection circuit into a plurality of parts and provide them in regions other than the semiconductor chip region.
However, a problem occurs such that an inspection for disconnection in lead wires from mounting terminals of semiconductor chips to a display plane cannot be performed. To solve the problem, a method of providing an inspection circuit intended to perform an inspection for disconnection in lead wires in a semiconductor chip mounting region is proposed (refer to, for example, Japanese Patent Application Laid-Open No. 2011-154161).
According to the method described in Japanese Patent Application Laid-Open No. 2011-154161, regardless of increase in the resolution of display panels and increase in the density of semiconductor chips, wires in a display plane, semiconductor elements, and wires from mounting terminals of semiconductor chips to the display plane can be inspected. However, the lighting state has to be checked in practice, so that an inspection has to be performed after a manufacturing process is carried out to a level at which displaying is possible. For example, in the case of a liquid crystal display device, the manufacturing process has to be carried out to a process of overlapping an array substrate and an opposed substrate and sealing liquid crystal between the substrates. There is, consequently, a problem such that in the case where it is found out that something is wrong with the array substrate at this manufacturing stage, the opposed substrate, the liquid crystal, and the cost of the manufacture up to the stage are wasted.